The unsubstituted 1,2,3,4,5,6-hexahydro-1,6-methano-3-benzazocines have been shown to be potent analgesics which have no physical dependence capacity and a number of other desireable properties. The synthesis of a number of substituted members of this series will be undertaken with the hope that a clinically useful drug will result. A number of other ring systems, which analogy suggests might possess analgetic activity, will also be prepared and pharmacologically evaluated. The problem of opioid - opioid receptor site interaction is one that requires a knowledge of the conformation of the opioids in solution. Nuclear magnetic resonance spectroscopy combined with lanthanide shift reagents will be employed to determine the solution conformations of representative compounds to substantiate present opioid - opioid receptor site interaction theories.